PROJECT SUMMARY/ABSTRACT While a large focus of research on U.S. college drinking has focused on the prevalence of and problems related to heavy-episodic drinking, a much smaller amount of research has focused on college students who are either abstainers (i.e., do not drink any alcohol) or lighter drinkers (i.e., for men, drinking 4 or fewer drinks in two hours and 14 or fewer drinks per week; and for women drinking 3 or fewer in two hours and 7 or fewer drinks per week). According to a national survey, over 40% percent of college students ages 18?22 do not report drinking in the past month (SAMSHA, 2014) with only half of those engaging in regular heavy-episodic drinking (NIAAA factsheet). Research further suggests that a significant proportion of students who were abstinent or light drinkers prior to and upon entering college do initiate drinking, and often progress to becoming heavy-episodic drinkers (McCabe et al., 2005; O'Malley & Johnston, 2002; Schulenberg et al., 2005). This provides evidence that the first year of college, and specifically the first few months, is a high-risk time for initiating both drinking and heavy-episodic drinking and that delaying the onset of heavy-episodic drinking among light drinkers and abstainers should lead to greater related harms throughout both the college years and young adulthood. Additionally, mobile phone-based interventions are an innovative method for reaching young people and have been established as an evidence-based, recommended approach towards addressing health issues (Free et al., 2011), including alcohol use (Suffoletto et al., 2012). As such, the ultimate goal of this proposal is to develop, refine and pilot a text message (TM) intervention for abstainer and lighter drinking first year college students with the ultimate goal of delaying alcohol initiation and/or reducing alcohol use escalation. An iterative process of focus groups, intervention content development, and user feedback focused on the unique experiences of abstainers and lighter drinkers will inform the TM Intervention to be delivered in a pilot study with 6 weeks of TMs, a 6 week post-intervention assessment, and 3, 6, and 9 month follow-ups and among 100 incoming first year abstainer and lighter drinker college students. The proposed research has great potential for impact on public health. Although TM interventions have been used with high-risk young adult drinkers, this is the first TM intervention to be developed for abstaining or lighter drinkers, which is a noted gap in the literature (Bock et al., 2016). Delaying alcohol use initiation or escalation to heavy alcohol use will, in the longer-term, save money and effort associated with higher-risk alcohol use. Given that reducing young adults' and college students' engagement in excessive alcohol use has been listed as a major objective of Healthy People 2020 (USDHHS, 2015) and a key priority of NIAAA, an intervention that focuses on delaying alcohol initiation and escalation into higher-risk alcohol use among abstainer and lighter drinkers could make important strides to achieving this goal.